Johnnie St. Vrain: Band doesn't harm eagles in the long run

This bald eagle, in mid flight, was photographed by Ben Gallagher, near Mead, recently. (Photo submitted by Ben Gallagher)

Dear Johnnie: I noticed in the lovely photo of the eagle on page 3 of the July 30 issue that one of the eagle's legs has a band on it. I also noticed the banded leg has a much smaller claw than the unbanded leg.

Is this because the band was likely placed on the eagle when it was a juvenile, and as the eagle's leg grew the band became too tight, which didn't allow the claw to develop and grow normally? -- Eagle Eye

Dear Eagle Eye: I, too, noticed the band and the apparent size difference between the claws, so I checked with the U.S. Fish & Wildlife Service.

Stephanie Jones, nongame migratory bird coordinator for the USFWS' Mountain-Prairie Region, returned my call. Her perspective of the photo was different from yours and mine.

Ben Gallagher took this photo of an adult bald eagle in flight. The eagle, with another adult and two juveniles, had just finished a prairie dog dinner and had used its both claws to dig into the dog. (Ben Gallagher, courtesy photo)
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"Birds are not people," she said. "They don't grow after they leave the nest. What changes is their feathers and their weight. But their bone structure develops in the nest and never changes."

Her point was that juvenile eagles are the same size as adults, so if this eagle had been banded as a juvenile (which was a possibility), its leg would not have grown larger after it was banded.

And she made another point: Wildlife officers who band raptors know what they are doing and would not band a bird in a way that would damage its leg or hinder its growth.

Could one leg have naturally been underdeveloped? Unlikely, Jones said, because the birds that survive to adulthood are those without deformities. Despite the appearance in the photo, she said, this eagle's claws are the same size. I had to take her word for it; she's the wildlife biologist. "I have banded 20,000 birds," she said.

Barr Lake bald eagles

A bald eagle nest can be viewed at Barr Lake, just east of Interstate 76 at 136th Avenue. To read more about the eagles at Barr Lake, go to http://bit.ly/S3AYZX.

But just to be sure, I called the photographer, Ben Gallagher.

He told me that he had happened upon four bald eagles -- two adults and two juveniles -- in a field.

"He was really close, and he was actually eating a prairie dog. I sat there for a few minutes and watched him," Gallagher told me. "The claw is definitely functional."

Gallagher was kind enough to send me more photos, so that I could get a better look at that claw. One of the photos, of the eagle flying directly toward him, makes it appear as if the claws are closer in size. It was taken after the eagle was eating the prairie dog, so it is possible that the eagle has a bit of prairie dog in that claw.

So, why and how would someone band a bald eagle's leg?

"There are political reasons and biological reasons," Johnson said.

In this photo taken recently near Mead, a bald eagle enjoys a lunch of prairie dog. Note the band on its leg. (Ben Gallagher/courtesy photo)
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"A political reason: At DIA, they worry about birds of that size hitting planes, so they'll capture birds ... and move them a long way away. They band it so they'll know if it comes back."

"A biological reason: To find out how big its territory is, how long it lives, where it migrates, where it breeds, where it winters, and how it travels between the two."

So, if a bird is captured and banded in one place, and captured in another, biologists can learn about its habits.

"The (band) numbers are federally issued. They are unique," Jones said. "You have to have a permit and a lot of training."

Adult birds can be trapped and banded. The process takes two people and includes putting a falconer's hood over the eagle's head. Juveniles can be banded while still in the nest.

Jones relayed a story about a co-worker who climbed to a bald eagle's nest in Alaska to band an eaglet. The man successfully banded the bird but returned "with striations on his back," she said. "The adults object strenuously when you do this with a young eagle in the nest."

A juvenile bald eagle calls out to another juvenile in a field near Mead. (Ben Gallagher/courtesy photo)
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